A new baby oviraptorid, Gobiraptor minutus, from Cretaceous Mongolia that may have eaten bivalves source

The first stegosaur named in Mongolia, Mongolostegus exspectabilis, may be the most recent stegosaur found to date source

A new article in Nature shows that two-thirds of 3D scan data is not shared online, largely so authors can exclusively use it for future work source

The Montana House of Representatives passed the bill that says fossils are part of a property’s surface estate, not the mineral estate source

The National Showcaves Centre for Wales sold a 15ft tall 30 ft long Allosaurus sculpture to make space for new sculptures source

The dinosaur of the day: Dromaeosaurus

Theropod that lived in the Late Cretaceous in what is now the western U.S. and Alberta, Canada

Not many fossils found

Holotype includes a partial skull (missing most of the top of the snout), and some foot bones

Discovery of other dromaeosaurids have helped fill in the gaps about Dromaeosaurus (Dakotaraptor, Utahraptor, other raptors, etc.)

About 6.6 ft (2 m) long and weighed about 33 lb (15 kg)

Had a robust skull, and sharp teeth

Phil Currie published a study of Dromaeosaurus in 1994 and said the “braincase bones are not pneumatized” (heavy)

Probably had a good sense of smell

Had robust teeth, that had a lot of wear and tear (probably used to crush and tear, or “puncture and pull”, not slice flesh)

Therrien and others in 2005 said Dromaeosaurus’ bite was almost three times more powerful than Velociraptor and may have used its jaws more than its sickle claw

May have gone after large prey, and may have eaten bone (similar feeding strategy to tyrannosaurids)

Had a sickle claw on each foot

Type species is Dromaeosaurus albertensis

Described in 1922 by William Diller Matthew and Barnum Brown

Name means “swift running lizard”

Species name refers to Alberta

Fossils found in 1914 on an American Museum of Natural History expedition at Red Deer River (area now part of Dinosaur Provincial Park)

Seven other species were named, mostly based on fragments. Some have been reclassified as other genera (Troodon, Velociraptor), and the rest are considered nomina dubia.

Matthew and Brown put Dromaeosaurus in its own subfamily Dromaeosaurinae, under Deinodontidae, but in 1969 John Ostrom said it was similar to Velociraptor and Deinonychus, and assigned them to Dromaeosauridae (many more dinosaurs found, so there are lots of subfamilies within Dromaeosauridae, including Dromaeosaurinae)

Dromaeosaurs were small to medium sized feathered carnivorous theropods that lived in the Cretaceous

They’re often known as raptors (one of the most famous ones is Velociraptor)

Found all over the world, on six continents, and possibly some teeth in Australia (so maybe all seven continents)

Closely related to birds

Bob Bakker and John Ostrom used droameosaurs (Deinonychus) to show dinosaurs were fast and smart, and related to modern birds

Generally they had large skulls, serrated teeth, good binocular vision, large hands, long tails, and sickle claws on their feet (kept this toe off the ground when walking), and probably all were feathered

Can see a cast at the Royal Tyrrell Museum’s Field Station (pack of Dromaeosaurus attacking a Lambeosaurus)

Fun Fact:
Mongolostegus/Wuerhosaurus may be the most recent stegosaur, but there have been more recent tracks found in Australia, so that might be a good place to find a more recent stegosaur.

Hadrosaurid that lived in the Cretaceous in what is now Montana, US, and Alberta, Canada (found skeletons and bonebeds in the Judith River Formation and the Oldman Formation)

Name means “short-crested lizard”

Described in 1953 by Charles Mortram Sternberg, based on a skull and partial skeleton

Sternberg found the fossils in 1936 in Alberta, and at first thought they were Gryposaurus

Type species is Brachylophosaurus canadensis

Species named refers to the fact that it was found in Canada

Later, it was found that a partial skull discovered in 1922 could be referred to Brachylophosaurus canadensis

In 1988 Jack Horner described a second species, Brachylophosaurus goodwini (named in honor of collector and preparator Mark Goodwin), found in the Judith River Formation (though in 2005 Albert Prieto-Márquez said the differences between the two species were either because of individual variation or the result of the second species specimen being reconstructred with an upside down skull crest

More specimens have since been found in both Alberta and Montana (though more were have been found in Montana now, especially since a bonebed was found near Malta, Montana, and has over 800 specimens)

About 30 ft (9 m) long as an adult, though Gregory Paul estimated it to be 36 ft (11 m) long and weighing 7 tons

Had a relatively small head, long lower arms, and a wide upper jaw beak, covered in a sheath

Had cheeks to keep food in and dental batteries, and continually replaced teeth

Head was elongated (wide at the rear and narrow along most of the snout)

Had large nostrils

Had a bony crest, which was flat and paddle-like over the top of the back of its head, and had a ridge on the midline (also, was not hollow)

Crests varied, depending on age (some covered most of the skull, others were shorter and narrower)

May have had sexual dimorphism, where males had larger crests than females for display

Crest may have been used for pushing contests for display (not enough evidence to know for sure)

Soft tissues have been found in Brachylophosaurus “mummies” (tissue replaced by minerals, so it’s the fossil of a mummy)

Most famous “mummy” is nicknamed “Leonardo”. Leonardo is 90% covered in soft tissue, and shows that the base of the neck had a lot of muscle, that there were small polygonal scales on the broad beak, there was a midline frill on the back made by triangular-shaped projections, and that the second, third, and fourth fingers on its hands were in a soft tissue so it looked like a mitten

Leonardo was found in the bonebed in 2000, by Dan Stephenson

Leonardo got his name because graffiti near where it was found said “Leonard Webb and Geneva Jordan, 1917”

Leonardo was a juvenile when it died, and was 22 ft (7 m) long and weighed between 1.5 and 2 tons

Leonardo had pebbly skin texture

Leonardo’s gut contents were preserved: ferns, confiers, magnolias, and pollen from more than 40 different plants

Leonardo also had small, needle-like worm parasites in its stomach (other dinosaurs may have also had parasites)

Lived in a wet enivornment, and mummification usually happens in dry conditions, so not clear how it was mummified (soft tissues may have been preserved another way before the body decomposed)

In 1994 in Malta, Montana, Nate Murphy found a complete, well preserved Brachylophosaurus that he nicknamed “Elvis”

Other specimens found include “Roberta,” (almost complete), “Peanut” (juvenile with skin impressions), and “Marco”

Peanut is on display at the Judith River Dinosaur Institute in Malta, Montana

Evidence of tumors were found in Brachylophosaurus skeletons in a 2003 study

Tumors may be a sign of inbreeding (not enough genetic diversity, leads to the increase of tumors)

Other dinosaurs that lived in the same time and place include the ceratopsian Chasmosaurus, the hadrosaur Parasaurolophus, the tyrannosaurs Daspletosaurus and Gorgosaurus, and the troodont Troodon

Fun Fact:

Sir Richard Owen named Dinosauria, but the three animals he based the group on were all named by Gideon Mantell. Owen also thought Dinosaurs were related to pachyderms (a dubious name for elephants, rhinos & hippos).

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Found in 2014 and 2015 by brothers and amateur paleontologists Nick and Rob Hanigan, near Penarth in Wales. They were look for ichthyosaurs and found boulders, with dinosaur bones sticking out of them, that had fallen from a cliff face

Described in 2016 by David Martill, Steven Vidovic, Cindy Howells, and John Nudds

Nick and Rob suggested the genus name

Type species is Dracoraptor hanigani

The species name is in honor of the Hanigan brothers

Found in the Blue Lias Formation (right between a layer with a Jurassic ammonite and a layer that represents the Triassic-Jurassic boundary)

Skull is about two-thirds complete, but was disarticulated

Juvenile specimen found, and was 7 ft (2.1 m) long

Adults could have grown up to 10 ft (3 m) long

Bipedal, with a long tail

Had dagger-shaped, serrated teeth

Had small teeth (.4 in or 1 cm) long, so it probably ate small lizards and mammals

Had a furcula (wishbone)

Had long legs and was probably a fast runner

The Dracoraptor specimen probably was washed into sea, but the paleontologists who described it tentatively said it was a “shore-dwelling animal”

Dracoraptor is the oldest Jurassic dinosaur known, so far

Most complete theropod from Wales, so far

Basal Neotheropoda, and the most basal coelophysoid

Only had three teeth in the premaxilla, which is a basal trait

Vidovoc said, “So this dinosaur starts to fill in some gaps in our knowledge about the dinosaurs that survived the Triassic extinction and gave rise to all the dinosaurs that we know from Jurassic Park, books and TV”

Today’s podcast is brought to you by audible.com. Get a free audiobook download and 30 day free trial at audibletrial.com/IKnowDino. Over 180,000 titles to choose from for your iPhone, Android, Kindle or mp3 player.

Lambe was referencing the nasal arch, which resembled a gryphin (for the name “hooked beak”)

Had a narrow, arching nasal hump, that some have described as like a “Roman nose”

The term “gryposaur” is sometimes used to hadrosaurs with nasal arches

Lived in the Late Cretaceous in North America

Found in Dinosaur Park Formation in Alberta, Canada, Two Medicine Formation in Montana, and Kaiparowits Formation in Utah

Similar to Kritosaurus, and for a while it was thought they were synonyms (long history)

First fossils were collected in 1913 by George Sternberg, from Dinosaur Park Formation in Alberta. Found a skull and partial skeleton

Multiple skulls, some skeletons, and some skin impressions have been found

Lawrence Lambe described Gryposaurus in 1914

A few years before the Gryposaurus find, in 1910, Barnum Brown had found and described a partial skull from New Mexico, and called it Kritosaurusnavajovius

Brown’s specimen did not have a snout, so he restored it based on Anatotian (now Edmontosaurus), which had a flat-head

Lambe described Gryposaurus differently (focused on the nasal crest), and in 1916 the Kritosaurus skull was remade to have the nasal arch. Barnum Brown and Charles Gilmore suggested the two were synonyms

This influenced William Park’s decision to name a nearly complete skeleton found in Dinosaur Park Formation Kritosaurusincurvimanus, instead of Gryposaurusincurvimanus (and he let Gryposaurus notabilis stay as its own genus)

Parks considered Gryposaurus to be a junior synonym of Kritosaurus

Hard to compare Kritosaurusincurvimanus and Gryposaurus notabilis because Kritosaurus incruvimanus is missing part of the front of the skull, so we don’t see the full nasal arch

Kritosaurus is only known from partial remians and seem very similar to Gryposaurus (except it lived a little later than Gryposaurus, based on the slightly younger formation where it was found)

In 1942, Lull and Wright published a monograph on hadrosaurs and said Kritosaurus and Gryposaurus were the same

But in the 1990s some scientists questioned Kritosaurusnavajovius (limited material compared to other hadrosaurs), so some think the two genera are different

Some scientists, such as Jack Horner, have suggested that Hadrosaurus is the same as Gryposaurus and Kritosaurus. This was a common hypothesis in the 1970s and 80s. But in 1990 Jack Horner changed his mind and said Gryposaurus was its own genera. Most scientists now think that Hadrosaurus and Gryposaurus have differences in their upper arms and iliums

Horner described the specimens of a second species, Gryposaurus This based based on two parts of skeleton that was collected in 1916 for AMNH (also there was bonebed material)

Three valid species: Gryposaurusnotabilis, Gryposauruslatidens, Gryposaurusmonumentensis (though could be 4-5, depending on who you ask)

Type species is Gryposaurusnotabilis

Gryposauruslatidens has an informal name, Hadrosauravus, that was used early on (no longer used)

There’s a possible fourth Gryposaurus species, Gryposaurusalsatei, found in the Javelina Formation

Stephanosaurusmarginatus was once considered to be a possible Kritosaurus species (when Kritosaurus and Gryposaurus were considered synonymous), but now it’s considered to be dubious

Jack Horner also created the new combination of Gryposaurusincurvimanus

Gryposaurus has been found in various places including Alberta, Utah, Montana, and possibly Texas, so it had a large geographical range

Gryposaurus lasted for at least 5 million years, which is a lot longer than most other taxon in Hadrosauridae (except Edmontosaurus)

Gryposauruslatidens is from the lower Two Medicine Formation in Montana, and lived about 4 million years before other Gryposaurus species appeared ( notabilis and G. incurvimanus), G. monumentensis is about 1-2 million years younger than G. notabilis and G. incurvimanus

Gryposaurusmounmentensis was named in 2007, by Natural History Museum of Utah paleontologists. Scott Sampson called it the “Arnold Schwarznegger of duck-billed dinosaurs”

Fossils found in Utah, a skull and partial skeleton, were named Gryposaurusmonumentensis (found in Grant Staircase-Escalante National Monument). Had a robust skull

Researchers first found Gryposaurusmonumentensis in 2003

Gryposaurusmonumentensis had thick bones in its skull and limbs

Gryposaurusmonumentensis had big jaws, so it could eat tough planet material

Gryposaurusmonumentensis had 300 teeth in its mouth for eating, but it had lots of replacement teeth, so at any time it may have had more than 800 teeth

Gryposaurus was bipedal and quadrupedal

Ate a variety of plants, and could eat food on the ground and up to 13 ft (4 m) off the ground

Ground its food (similar to chewing)

Cropped vegetation with its beak, and had cheek-like organ to keep food in its mouth

As Gryposaurus grew, its nasal arch got bigger

The arch was over an enlarged nasal opening, which may have held soft tissue

Nasal arch was probably covered by thick, keratinized skin, or had a cartilaginous extension

Nasal arch may have been for fighting each other, or for species or sexual dimorphism

Nasal arch may also have been used to help push or butt in contests, and it may have had inflatable air sacs (visual and audio signals)

About 30 ft (9 m) long, though one species

Had scales along the midline of its back

Had pyramidal and ridged scales

Saurolophine hadrosaurid (subfamily with hollow crests on their heads)

Gryposaurus was for a while considered to be a hadrosaurine, but then Hadrosaurus was found to be different from other dinosaurs classified as hadrosaurines. Then Hadrosaurus was given a place beneath Hadrosauridae, but hadrosaurinae could no longer be used because it didn’t include Hadrosaurus. So the next oldest genus in that group, Saurolophus, becuase the type genus of Saurolophinae, and now Gryposaurus is considered to be a saurolophine

Probably lived on a floodplain with swamps, ponds, lakes, in a wet and humid climate

May have preferred being by the river

Other dinosaurs that lived in the same time and place include Centrosaurus and Corythosaurus, dromaeosaurids, troodontids, ornithomimids, ankylosaurids, tyrannosaurids (Albertosaurus and Teratophoneus), Parasaurolophus, ceratopsians such as Utahceratops and Nasutoceratops, and oviraptorosaurians such as Hagryphus

Also lived among sharks and rays, frogs, salamanders, turtles, lizards, crocodilians, and early mammals (marsupials and insectivorans)

Where Gryposaurus lived was a relatively small area, and there were other hadrosaur species around at the same time and place. Yet, they didn’t seem to intermingle, and it’s unclear why (since there were no known physical barriers, like mountains, to get in their way). It’s also not clear how such a relatively small area support so many large herbivores. One hypothesis is that hadrosaurs and other large herbivores had slower metabolisms, or maybe there were a large amounts of plants to eat, or the climate in the area, known as “West America” varied across latitudes, so plants in different areas would have been different, and that’s why dinosaurs may not have mixed

Fun Fact:

Japan was connected to the rest of Laurasia for the entire Mesozoic, so dinosaurs could come and go freely

Brief history summarized from Origins of the Japanese Islands: The New “BigPicture” By Gina L Barnes Published in Japan Review:

One species: Gorgosaurus libratus (other species have been assigned, though they were not correct)

Species name means “balanced”

Described in 1914 by Lawrence Lambe

Holotype is a nearly complete skeleton and a skull, found by Charles M. Sternberg in 1913 in Dinosaur Park Formation in Alberta, and was the first tyrannosaurid found with a complete hand

At least 12 Gorgosaurus specimens have been found

AMNH collected hundreds of dinosaur specimens around that time, and found four complete Gorgosaurus skulls, three with skeletons. Matthew and Brown described them in 1923

Matthew and Brown described a 5th skeleton (Charles Sternberg found in 1917 and sold to AMNH). It was smaller than other specimens, and similar to other juvenile tyrannosaurids, with longer limb proportions and a lower, lighter skull, but they said it was a new species, Gorgosaurus sternbergi (now considered to be a juvenile Gorgosaurus libratus)

Most closely related to Albertosaurus (also distantly related to T-rex)

Part of the subfamily Albertosaurinae (more closely related to Albertosaurus). Albertosaurinae had more slender builds, were smaller, had lower skulls, and longer tibias

Very similar to Albertosaurus, but subtle differences in teeth and skull

Some people think Gorgosaurus libratus is Albertosaurus (Gorgosaurus would be a junior synonym, since Albertosaurus was named first)

In 2003 a team found that Gorgosaurus was different from Albertosaurus (had slightly longer legs, and skull was a little different. Gorgosaurus was mostly found in older rocks than the majority of Albertosaurus fossils, so some think Gorgosaurus was an ancestor to Albertosaurus)

William Diller Matthew and Barnum Brown thought Gorgosaurus and Albertosaurus were the same in 1922, and Dale Russell formally reassigned Gorgosaurus to Albertosaurus libratus in 1970, but not everyone agrees (including Phil Currie, who said there are undescribed tyrannosaurids from Alaska, New Mexico and other parts of North America that could help answer the question). Gregory Paul said Gorgosaurus may be ancestral to Albertosaurussarcophagus

Some species were incorrectly named Gorgosaurus, including a small tyrannosaurid from Hell Creek (named by Charles Gilmore in 1946 as Gorgosauruslancensis and since renamed Nanotyrannus by Bob Bakker in 1988, which some people now think is just a juvenile T-rex). In 1955, Evgeny Maleev named Gorgosaurus lancinator and Gorgosaurus novojilovi from two tyrannosaurids found in Mongolia, but in 1992 Kenneth Carpenter renamed the one Maleevosaurus novojilovi, and now they’re both considered to be juvenile Tarbosaurus bataar

In 1856, Joseph Leidy described two tyrannosaurid teeth (nothing else of the animal found) and called them Deinodon. Matthew and Brown said in 1922 they were the same as Gorgosaurus teeth, but since there were no other fossils they did not synonimize them, and called it Deinodon libratus (however, tyrannosaurid teeth in general look the same, so not for sure it is Gorgosaurus). Deinodon is usually considered to be a nomen dubium now

Some tyrannosaurids from Two Medicine and Judith River in Montana are probably Gorgosaurus (not clear if it’s Gorgosaurus libratus or a new species).

One specimen, now at the Children’s Museum in Indianapolis, has a number of pathologies (healed leg, rib fractures, infection that led to permanent tooth loss, and possibly a brain tumor)

Holotype had some pathologies, including healed fractures and a deformed toe, possible from a fight with another dinosaur

Another Gorgosaurus had many pathologies (fractures, multiple ribs healed from fractures, lesions from a bite on the face), evidence that it was healing before it died

Another Gorgosaurus had bite marks on its face, as well as a “mushroom-like hyperostosis of a right pedal phalanx” that may be similar to a pathology found on an unidentified ornithomimid

Gorgosaurus was an apex predator that fed on ceratopsids and hadrosaurs

Co-existed with Daspletosaurus (similar in size, but possibly there was some niche differentiation)

Rare for two tyrannosaur genera to co-exist. Some thought Gorgosaurus hunted the hadrosaurs and Daspletosaurus went for the ceratopsids, but one Daspletosaurus was found with a hadrosaur in its gut, and a Daspletosaurus bonebed had three Daspletosaurus with five hadrosaurs (no evidence of Gorgosaurus pack behavior)

Gorgosaurus appears to be more common in the north and Daspletosaurus in the south

Skull was a little smaller than Daspletosaurus (39 in or 99 cm long), but large for its body (had large fenestrae to reduce weight)

Grew up to 26-30 ft (8-9 m) long and weighed about 2.5 tons

Gorgosaurus was a juvenile for about half its life, and then had rapid growth spurts. Since no intermediate size predators have really been found, the juveniles probably filled a niche (similar to Komodo dragons)

Smaller Gorgosaurus that were found had longer tibias than femurs, so were fast running

As a juvenile, Gorgosaurus probably went after ornithomimids (faster prey)

Adult Gorgosaurus had long hindlimbs (largest Gorgosaurus femur was 41 in or 105 cm long)

Had two-fingered forelimbs (forelimbs were small, proportionately)

Had two digits on each forelimb, and four digits on each hindlimb (first digit didn’t touch the ground)

Had a blunt snout, and nasal bones were fused

Had a circular eye socket

Had crests in front of eyes, like Albertosaurus and Daspletosaurus

Had 26-30 maxillary teeth and 30-34 teeth in the lower jaw

Had a heavy tail

Phil Currie found skin impressions in 2001, and it was smooth (like secondarily flightless birds skin) and didn’t have scales (though scales were found on the specimen, but were widely dispersed and small, and other patches of skin had denser, larger scales). This helps show that bigger dinosaurs didn’t have feathers, since larger animals naturally lost less heat due to the smaller surface area to body volume ratio

Tyrannosauridae (means “tyrant lizards”) are theropods

Lived late Cretaceous, Asia and North America

Usually the largest predators

Not many complete specimens found for known tyrannosaurids

But many genera have complete skulls

Some tyrannosaurids had crests above eyes

Small arms but long legs

Juvenile tyrannosaurids had longer legs, more suited to running fast, but that changed as adults

Fun fact:

Birds don’t only use feathers for flight, display, camouflage, physical protection, sensory inputs, water proofing, and insulation in the cold, but also for staying cool in the sun. A study back in 2004 compared kangaroos and emus in harsh sun in the Australian Outback and found that kangaroos could dissipate 75–85% of solar radiation with their fur but Emus could dissipate nearly 100% of solar radiation with their feathers despite the fact that have darker colors. This allows emus to stay in the sun while Kangaroos stay in the shade in the summer.

Allosaurus T-shirt (Limited Time!)

We have an Allosaurus t-shirt on sale at Teespring. Hurry, it’s only up for sale until March 27! Special thanks to artist Josh Cotton, the Doodling Dino, for the awesome drawing. Get it here: